fix range

mshadow/extension/range.h

@@ -23,9 +23,9 @@ namespace expr {
 template<typename DType>
 struct RangeExp:
       public Exp<RangeExp<DType>, DType, type::kMapper> {
-  const float start_;
-  const float stop_;
-  const float step_;
+  const DType start_;
+  const DType stop_;
+  const DType step_;
   const int repeat_;
   /*! \brief constructor */
   RangeExp(DType start, DType stop, DType step, int repeat)
@@ -67,18 +67,26 @@ MakePlan(const RangeExp<DType> &exp) {
   return Plan<RangeExp<DType>, DType>(exp);
 }
 
-inline int RangeOutSize(float start, float stop, float step, int repeat) {
-  return repeat * static_cast<int>(ceil((stop - start) / step));
+
+template<typename DType>
+inline int RangeOutSize(DType start, DType stop, DType step, int repeat) {
+  return repeat * ((stop - start - 1) / step + 1);
 }
 
-inline int RangeOutSize(double start, double stop, float step, int repeat) {
-  return repeat * static_cast<int>(ceil((stop - start) / step));
+template<>
+inline int RangeOutSize<float>(float start, float stop, float step, int repeat) {
+  double d_start = static_cast<double>(start);
+  double d_stop = static_cast<double>(stop);
+  double d_step = static_cast<double>(step);
+  return repeat * static_cast<int>(ceil((d_stop - d_start) / d_step));
 }
 
-inline int RangeOutSize(int start, int stop, int step, int repeat) {
-  return repeat * ((stop - start - 1) / step + 1);
+template<>
+inline int RangeOutSize<double>(double start, double stop, double step, int repeat) {
+  return repeat * static_cast<int>(ceil((stop - start) / step));
 }
 
+
 template<int dim, typename DType>
 struct ShapeCheck<dim, RangeExp<DType> > {
   inline static Shape<dim>
@@ -96,7 +104,7 @@ struct ShapeCheck<dim, RangeExp<DType> > {
       CHECK(t.start_ > t.stop_) << "RangeExp does not support (start, stop, step)= "
                                 << "(" << t.start_ << "," << t.stop_ << "," << t.step_ << ")";
     }
-    return Shape1(RangeOutSize(t.start_, t.stop_, t.step_, t.repeat_));
+    return Shape1(RangeOutSize<DType>(t.start_, t.stop_, t.step_, t.repeat_));
   }
 };